The invention relates to improvements in paper machines, and more particularly to an improved pressing arrangement for dewatering a web received from a forming section of a papermaking machine.
In a press section of a papermaking machine, an important object is to remove as much water from the web as possible without damaging the formation or crushing the web. It is a well known fact that with every additional removal of even a fraction of a percent of water from the web, great savings in energy are accomplished. The water which is not removed in the press must be removed thermally in the dryer drum section of the paper machine, and the energy requirements for the removal of a unit of water by evaporation greatly exceed the energy requirements for removal of the same unit of water by pressing.
It is well known from a review of the pressing art that a great many press arrangements have been proposed and used with varying degrees of success. It is not apparent from a study of the pressing art or the pressing structure arrangements available in the art what changes should be made to improve pressing operation and improved presses have been arrived at substantially wholly through discovery and invention because minor variances can often effect substantial improvement in water removal without any prior indication as to why such variance should accomplish an improvement. The combinations and permutations of arrangements of felts and press rolls are substantially infinite, but with these infinite permutations and combinations, many arrangements will not effect improvements in dewatering and many will essentially be inoperative because of too much water being left in the web or because of the web experiencing crushing or other phenomena which results in a poor paper sheet at the delivery end of the machine.
It is accordingly an object of the present invention to provide an improved paper machine press section which is capable of removing an increased amount of water from a traveling web and is capable of satisfactory dewatering at higher machine speeds.
A further object of the invention is to provide an improved paper machine press which utilizes the improved effects of an extended nip press and utilizes a combination of a conventional two roll press with an extended nip press. A still further object of the present invention is to provide an improvement in papermaking machines for providing an improved quality web and reducing energy requirements of a papermaking machine by an improved press section.
Other objects, advantages and features will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiment thereof in the specification, claims and drawings, in which: